1. Field of the Invention
The present invention relates to a multi-joint type industrial robot with a plurality of arms respectively coupled by a plurality of revolving joints, which is used, for example, for conveying semiconductor wafers in manufacturing process of semiconductor devices, and relates to an arm unit of the industrial robot.
2. Description of the Related Art
An industrial robot with a plurality of revolving joints which are horizontally arranged is conventionally used for conveying works such as semiconductor wafers in a manufacturing facility of semiconductor devices. A configuration of the conventional industrial robot 81 with a plurality of joints is illustrated in FIGS. 4 and 5. In the industrial robot 81, a first motor 83 is provided in a mounting base 82. A first arm 84 is coupled with a drive shaft 83a of the first motor 83 in the vicinity of an end of the first arm 84. A second motor 85 is provided in the vicinity of another end of the first arm 84. A second arm 86 is coupled with a drive shaft 85a of a second motor 85 in the vicinity of an end of the second arm 86. A third motor 87 is provided in the vicinity of another end of the second arm 86. A robotic hand 88 for nipping a work such as a semiconductor wafer is coupled with a drive shaft 87a of the third motor 87 in the vicinity of an end of the robotic hand 88.
The first arm 84 is revolved by rotation force of the first motor 83. The second arm 86 is revolved by rotation force of the second motor 85. The robotic hand 88 is revolved by rotation force of the third motor 87. A sensor 89 for sensing the existence of the work is provided in the vicinity of a top end of the robotic hand 88.
A driving controller 90 is further provided in the mounting base 82. Electric cables 91, 92 and 93 are respectively provided for supplying the electric powers and driving signals to the first to third motors 83, 85 and 87. Furthermore, an electric cable 94 is provided for coupling the sensor 89 and the driving controller 90.
In the conventional industrial robot 81, the electric cables 92 to 94 are directly connected from the driving controller 90 to the motors 85 and 87 and the sensor 89, which are provided on the arms 84 and 86 and the robotic hand 88, so that the number of electric cabled drawn out from the mounting base 82 becomes larger. Since the electric cables 92 to 94 are aligned along the lengthwise directions of the arms 84 and 86 and the robotic hand 88, the electric cables 92 to 94 are easily broken down, and the alignment of the electric cables 92 to 94 becomes complex. And especially, when the number of the arms increases, the number of the motors also increases. Thus, the number of the electric cables drawn out from the mounting base and the coupled with the electric elements such as the motors will be increased in proportion to the number of arms. In the industrial robot with many arms, the breaking of electric cables is incident much easier, and the arrangement of the electric cables becomes much more complex.
An object of the present invention is to provide an industrial robot with a plurality of joints, by which the number of electric cables directly drawn out from the mounting base can be reduced so that the breaking of electric cables rarely occurs and the arrangement of the electric cables becomes easier.
An industrial robot in accordance with an aspect of the present invention has a plurality of arms coupled by a plurality of revolving joints, each of the arms can be moved by a driving force of a motor which drives each of the revolving joints. The industrial robot comprises a plurality of control circuits for controlling the motors which are provided on respective of the arms. The control circuits are respectively provided on the same arms as the motors are provided.
By such a configuration, the control circuit for controlling the driving of the motor, which is separated from a main control circuit for controlling whole of the industrial robot, is provided on the same arm as the motor is provided, so that a signal cable used for controlling the motor is only connected between the motor and the control circuit, so that the signal cable can be shortened. Since, there is no need to connect the signal cables between the motors and the main control circuit, the alignment of the control signal cables can be simplified, and the breaking of cables rarely occurs even when the arm is moved and the total length of the cables can be shortened.